A method of operating a synchronous motor having a stator that includes a set of electromagnets and a permanent magnet rotor. The synchronous motor is controlled by calculating in a flux controller a measure of a flux magnitude, which is the magnitude of the stator flux of the motor and by calculating in a load angle controller a measure of a load angle. Information about a desired motor torque or a reduced motor torque, which is smaller than the desired motor torque, is input to the load angle controller and the load angle controller calculates the measure of the load angle depending on the input motor torque. The measure of the flux magnitude is combined with the measure of the load angle to obtain commands for controlling electric currents of electromagnets of the stator, thereby directly controlling the stator flux. A flux limit value, which depends on a predetermined maximum value of the stator flux allowed for the motor which depends on a maximum value of an electric voltage, which is used to drive the currents through the stator electromagnets and which depends on the actual rotor speed, is repeatedly calculated. During acceleration of the rotor while the stator flux is smaller than the maximum flux allowed for the motor the measure of the flux magnitude is calculated depending on the output of a predetermined function. The output of the predetermined function depends on the desired motor torque and corresponds to the magnitude of the stator flux.